I think this is one for Da'Umpire to look at, It looks like we have been playing terrain effects all wrong, i.e ice flows, crevasses etc.

this is a quote from page 13 of the Frostbite book:

Élysée is wide stretches of wilderness in between a handful of military bases, industrial sites and small colonies. Every terrain has its own characteristics and some of them have special rules presented here. A fighter is considered to be on a particular terrain when at least half his base is on it. A unit is considered on a terrain when at least half its members are on it.